Valid pathing: eight-port array LUN group configuration

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You can use an eight-port LUN group configuration to connect storage arrays with ONTAP systems in large clustered deployments that require greater path redundancy and load balancing than possible with fewer ports per LUN group.

You can set up this configuration with the back-end connections crossed or uncrossed.

Variation in which back-end connections are crossed

In a configuration with the back-end connections crossed, the FC connections from the same storage array controller go to both fabric switches (redundant).

This connection scheme makes better use of both switch ports and storage array ports than if the back-end connections are not crossed, which reduces the impact of a switch or storage array controller failure.

For storage arrays with only two controllers, a crossed eight-port LUN group configuration is preferred over an eight-port array LUN group configuration that is not crossed.

You can only cross the eight-port array LUN group when there are dedicated paths from each node (one FC initiator-to-one-target-port zoning per path).

eight port array lun group configuration crossed

In this illustration of crossed back-end connections, note how the ONTAP systems are attached to the switches and to the storage array. Vs1 uses switch 1 when attaching to the storage array Controller 1 port 1A and Controller 2 port 2C, and uses switch 2 when attaching to storage array Controller 2 ports 2A and Controller 1 port 1C.

The following table summarizes the zoning for an eight-port array LUN group with crossed back-end connections. Single-initiator zoning is the recommended zoning strategy.

Zone FC initiator port on the ONTAP system Storage array

Switch 1

z1

vs1, Port 0a

Controller 1, Port 1A

z2

vs2, Port 0a

Controller 1, Port 1B

z3

vs1, Port 0b

Controller 2, Port 2C

z4

vs2, Port 0b

Controller 2, Port 2D

Switch 2

z5

vs1, Port 0c

Controller 2, Port 2A

z6

vs2, Port 0c

Controller 2, Port 2B

z7

vs1, Port 0d

Controller 1, Port 1C

z8

vs2, Port 0d

Controller 1, Port 1D

Variation in which back-end connections are not crossed

In a configuration in which the back-end connections are not crossed, the FC connections from the same storage array controller go to only one fabric switch.

The following illustration shows pathing in a configuration with an eight-port array LUN group in which the back-end connections are not crossed:

eight port array lun group configuration

The following table summarizes the zoning for an eight-port array LUN group when the back-end connections are not crossed. Single-initiator zoning is the recommended zoning strategy.

Zone FC initiator port on the ONTAP system Storage array

Switch 1

z1

vs1, Port 0a

Controller 1, Port 1A

z2

vs2, Port 0a

Controller 1, Port 1B

z3

vs1, Port 0b

Controller 1, Port 1C

z4

vs2, Port 0b

Controller 1, Port 1D

Switch 2

z5

vs1, Port 0c

Controller 2, Port 2A

z6

vs2, Port 0c

Controller 2, Port 2B

z7

vs1, Port 0d

Controller 2, Port 2C

z8

vs2, Port 0d

Controller 2, Port 2D

Considerations for maximum number of array LUNs per FC initiator

When setting up a configuration with an eight-port array LUN group, you cannot exceed the number of array LUNs that ONTAP supports per FC initiator port.